Detailed
Bedrock Photograph

A granite with an ultramylonite, sample 03MW0110 is
composed of K-feldspar (40%), plagioclase (35%), quartz (20%), chlorite
(3%), epidote (1%), and trace muscovite, sphene, and oxides. This sample
is characterized by an ultramylonite zone where differential strain is
concentrated in an otherwise unfoliated granite. Feldspar porphyries in
the granite are severely seritized and show perthite and antiperthite.
Large aggregates quartz in the matrix show interlocking grains. Chlorite
may have replace biotite and other mafics, and occurs commonly in
bundles. The ultramylonite is composed small, 0.5 mm porphyries of
K-feldspar, quartz, sphene, plagioclase and epidote in a matrix of
fine-grained quartz, epidote, and chlorite. It is approximately 10 mm
thick.